In recent years, a switch unit in which a movable contact element is mounted on a wiring board has been used as an input device for various types of electronic devices.
A conventional switch unit includes a movable contact element mounted on a wiring board, for example, as shown in PTL 1. A first stationary contact element (a second stationary contact 1a) having a circular shape and a second stationary contact element (a first stationary contact 1b) having an annular shape surrounding the first stationary contact element are disposed on the wiring board. The movable contact element is made of an elastic metal having an upwardly convex dome shape having a circular shape when viewed from above. The movable contact element is mounted on an upper surface of the wiring board such that an outer peripheral portion of the movable contact contacts the second stationary contact element. A central portion of the movable contact element faces the first stationary contact element with a predetermined gap in between. The movable contact element deforms upon being pressed in a direction in which the central portion of the movable contact element approaches the wiring board, thereby contacting the first stationary contact element. This configuration allows the conventional switch unit to electrically connect the first stationary contact element with the second stationary contact element via the movable contact element. In other words, the conventional switch unit is turned from an off-state in which the first stationary contact element is electrically insulated from the second stationary contact element to an on-state in which the first stationary contact element is electrically connected with the second stationary contact element.